1. Field of the Invention
The present invention relates to a precise positioning actuator for a head element such as a thin-film magnetic head element or an optical head element, to a head gimbal assembly (HGA), with the actuator, to a disk drive apparatus with the HGA and to a manufacturing method of an HGA.
2. Description of the Related Art
In a magnetic disk drive apparatus, thin-film magnetic head elements for writing magnetic information into and/or reading magnetic information from magnetic disks are in general formed on magnetic head sliders flying in operation above the rotating magnetic disks. The sliders are supported at top end sections of suspensions of HGAs, respectively.
Recently, recording and reproducing density along the radial direction or along the track width direction in the magnetic disk (track density) has rapidly increased in order to satisfy the requirement for ever increasing data storage capacities and densities in today""s magnetic disk drive apparatus. For advancing the track density, the position control of the magnetic head element with respect to the track in the magnetic disk by a voice coil motor (VCM) only has never presented enough accuracy.
In order to solve this problem, an additional actuator mechanism is mounted at a position nearer to the magnetic head slider than the VCM so as to perform fine precise positioning that cannot be realized by the VCM only. The techniques for realizing precise positioning of the magnetic head are described in for example U.S. Pat. No. 5,745,319 and Japanese patent publication No. 08180623 A.
Inventors of this application have been proposed a piggy-back structure actuator. This piggy-back structure actuator is formed by piezoelectric material of PZT in an I-character shape with one end section to be fixed to a suspension, the other end section to be fixed to a magnetic head slider and a pillar shaped movable arm connected between these end sections. On the suspension, stepwise stacked are the actuator and the magnetic head slider, namely, the actuator is caught between the suspension and the slider to form a stacked cantilever structure.
However, an HGA with such piggy-back structure actuator will have following various problems:
(1) Because of the stepwise stacked structure, a total thickness of the HGA around the magnetic head slider increases by the thickness of the actuator;
(2) The actuator as a whole consists of piezoelectric material such as PZT of a brittle material, and the actuator and the magnetic head slider are stacked to form a cantilever structure. A shock easily occurs with a moment and also shock resistance is very poor;
(3) Depending upon the size of the magnetic head slider, a travel of the magnetic head element during the precise positioning operation varies. Thus, it is difficult to obtain enough stroke;
(4) Because of three-dimensional and complicated attachment structure of the actuator, the handling at the time of an assembly of the HGA is very difficult and it is impossible to use a conventional HGA assembly equipment causing productivity to be very worse; and
(5) In order not to interfere with the movement of the actuator, it is necessary to assemble with keeping a gap between the actuator and the magnetic head slider and also between the actuator and the suspension. However, forming of such gap will more decrease the shock resistance and it is difficult to precisely keep the gap constant. Particularly since it is difficult to keep the suspension, the actuator and the magnetic head slider in parallel precisely, the head characteristics deteriorates.
It is therefore an object of the present invention to provide a precise positioning actuator for a head element, an HGA with the actuator, a disk drive apparatus with the HGA and a manufacturing method of an HGA, whereby a thickness of the HGA will not increase even if the actuator is mounted thereto.
Another object of the present invention is to provide a precise positioning actuator for a head element, an HGA with the actuator, a disk drive apparatus with the HGA and a manufacturing method of an HGA, whereby a shock resistance can be greatly improved.
A further object of the present invention is to provide a precise positioning actuator for a head element, an HGA with the actuator, a disk drive apparatus with the HGA and a manufacturing method of an HGA, whereby the productivity and also quality of the HGA can be greatly improved.
According to the present invention, a precise positioning actuator to be fixed with a head slider with at least one head element and with a support, for precisely positioning the at least one head element, includes a pair of movable arms capable of displacing in response to a drive signal applied to the actuator The head slider is caught in a space between the movable arms.
Since the head slider is caught in a space between the movable arms capable of displacing in response to a drive signal applied thereto, the thickness of an HGA around the head slider does not increase even if the actuator is attached. Thus, no modifications in size of a disk drive apparatus due to the mounting of the actuator is necessary. Also, since the actuator and the head slider are not stacked to form a cantilever structure, a shock resistance can be greatly improved. Furthermore, since the head slider is caught in between the movable arms, the top end sections of the movable arms, which actually transfer the displacement to the head slider, can be always positioned at the top end of the head slider. Thus, it is possible to provide a constant travel to the head slider even if its size changes, and therefore an enough stroke of the head element at the precise positioning operation can be always obtained.
It is preferred that the actuator further includes a base fixed to the support and that the movable arms extend from the base.
It is also preferred that the movable arms have at their top end sections slider fixing sections to be fixed to side surfaces of the head slider, respectively. In this case, preferably, the actuator has a shape so that there exists air gaps between the movable arms and side surfaces of the head slider except for the slider fixing sections, respectively.
It is also preferred that the base is made of an elastic sintered ceramic. Furthermore, it is preferred that each of the movable arms includes an arm member made of an elastic sintered ceramic, and a piezoelectric element formed on a side surface of the arm member. Since the main sections of the actuator are made of elastic sintered ceramic such as ZrO2 that is strong for bending, a shock resistance of the actuator itself increases.
It is preferred that the movable arms is constituted so that the head slider is linearly and laterally oscillated in response to the drive signal. Since the head slider displaces namely oscillates with linear motion not swinging or rotational motion, more precise positioning of the bead element can be expected.
It is also preferred that inner corners at coupling sections of the base and the movable arms have an obtuse angle plane shape or a smooth plane shape. Thus, the shock resistance of the actuator itself is extremely improved.
It is preferred that the actuator has a rough U-plane shape.
It is also preferred that the actuator has a thickness equal to or less than a thickness of a head slider to be caught.
It is preferred that a spacing between the pair of movable arms is determined to a value slightly shorter than a width of the head slider to be caught.
It is preferred that the at least one head element is at least one thin-film magnetic head element.
According to the present invention, an HGA includes a head slider with at least one head element, a support and the aforementioned precise positioning actuator fixed with the head slider and with the support for precisely positioning the at least one head element.
It is preferred that the movable arms of the actuator and the head slider are fixed with an adhesive.
It is also preferred that the actuator and the support are fixed with an adhesive or a solder.
According to the present invention, a disk drive apparatus having at least one HGA mentioned above.
Also, according to the present invention, a manufacturing method of an HGA includes a step of preparing a precise positioning actuator with a pair of movable arms capable of displacing in response to a drive signal applied thereto, a step of catching a head slider with at least one head element in a space between the movable arms of the actuator, and a step of fixing the actuator with the caught head slider to the support.
First, the head slider is caught in a space between the movable arms of the actuator, and then the actuator with the caught head slider is fixed to the support. Since assembling of the head slider and the actuator can be carried out on the flat plate, alignment of the slider and the actuator becomes easy resulting that a higher accuracy assembling can be expected. Also, since a thermosetting adhesive with excellent curing performance although it needs a long curing time can be used, a high quality assembly of the head slider and the actuator can be obtained. Furthermore, since the assembly has a simple shape, adhesion and electrical connection of the assembly with a suspension can be performed by using a general HGA assembling equipment resulting the productivity to extremely improve and thus the manufacturing cost to reduce.
It is preferred that the catching step includes fixing the head slider between the movable arms with an adhesive.
It is also preferred that a spacing between the pair of movable arms is slightly shorter than a width of the head slider to be caught, and that the catching step includes provisionally fixing the head slider between the movable arms by a pinching force of the movable arms. The provisional fixing can be attained without using any holder.
It is preferred that the catching step includes securely fixing the head slider to the movable arms by thermally curing the adhesive after the provisional fixing.
It is also preferred that the fixing step includes fixing the actuator to the support with an adhesive or a solder
Further objects and advantages of the present invention will be apparent from the following description of the preferred embodiments of the invention as illustrated in the accompanying drawings.